1. Field of the Invention
The invention generally relates to an instrument for vision testing. More particularly, the invention relates to an instrument for measuring near point of convergence (NPC) and near point of accommodation (NPA).
2. Background
Near point of convergence (NPC) is measured by bringing an object close to a user's eyes, and measuring the distance from the eyes at which the user begins to see double. Near point of accommodation (NPA) is measured by bringing an object close to a user's eyes, and measuring the distance from the eyes at which the object appears blurry to the user. Presently, devices for measuring NPC and NPA rely on manual measurements, recording and the use of crude tools. As such, an improved instrument for measuring NPC and NPA is needed.